Pathology and Treatment of Cerebral Disease. No. II

arises, and of disembarrassing the mind, if need be, of any preconceived ideas derived from the authority of books, however well written, and of teachers however eminent. Thus, it is only necessary to examine the records of Medicine for a few years in order to become convinced of the fallacy of almost all attempts to establish unerring principles of nosological arrangement, or to institute dogmatic principles of treatment. Much of the change observable in these respects is no doubt due to the influence of what maybe called " fashion" in medicine; but much more is unquestionably attributable to the increased spread of knowledge, to the improved methods of medical teaching, to the closer attention paid to anatomical investigation, to a better appreciation of physiological laws, and to more extended opportunities of medical research offered by the invention of the precise instruments in which our age lias lately been so prolific. To pass over the stethoscope, the laryngoscope, the sphygmograpli, as being unconnected with the present subject, the introduction of the ophthalmoscope has literally thrown a vivid ray of light into one of the darkest cliambersof cerebral pathology, and has enabled the surgeon and the physician to infer, from the condition of the retinal